Machine for manufacturing a lock tumbler

ABSTRACT

Machine for manufacturing a lock tumbler comprises means for driving a blank down a passageway past successive broaches against a punch in a socket at the end of the passageway. The socket is then moved laterally of the passageway so that the blank therein contacts a third broach and is finally ejected from the socket.

l Umted States Patent [151 ama sm Spain 1 1 Feb" 22, 11972 [54] MACHINE FOR MANUFACTURING A 1,501,317 7/1924 Donaldson ..29/566 X LOCK TUMBLER 3,259,928 7/1966 Wallace ..10/l0 X 3,445,870 5 1969 [(01 c ..10 20.5 [72] Inventor: Roy C. Spain, Box 190, Salem, Va. 24153 e l 22 i d; b 10, 1970 Primary Examiner-Andrew R. .luhasz Assistant Examiner-F. R. Bilinsky [21] APPL 10,187 AttorneyJohn B. Sponsler [52] U.S.Cl ..29/566, 29/558, 10/10 ABSTRACT [51] Int. Cl ..B23p 15/111 Machine for manufacturin g a lock tumbler comprises means [58] FieldofSearch ..29/56o,558,10/1252;g for driving a blank down a passageway past successive broaches against a punch in a socket at the end of the passageway. The socket is then moved laterally of the [56] References Cited passageway so that the blank therein contacts a third broach UNITED STATES PATENTS and is finally ejected from the socket. 2,843,861 7/1958 Gancly ..10/20.5 X 9 Claims, 12 Drawing Figures BACKGROUND OF THE INVENTION This application relates to a machine for manufacturing a special type of tumbler for use in cylinder locks in which the tumblers rotate during operation of the lock. In conventional cylinder locks the tumblers are axially translated but are not required to rotate. In locks of the type shown in my U.S. Pat. application, Ser. No. 627,243, on the other hand, the tumblers must rotate before they can be moved axially, and must consequently have certain structural features not found in con ventional tumblers.

The particular tumbler which this machine is designed to manufacture is shown in FIG. 12, and it will be seen that it comprises a deep longitudinal groove C, a shallow longitudinal groove D, and a projection E resulting from the displacement of material to form the depression F. The lower end of the tumbler has a chisel point G.

The specific object of the present invention is accordingly to provide a machine which will automatically produce a tumbler having features C, D, E, F and G from a blank such as that shown in FIG. 8, which blank may be produced by a conventional screw machine.

SUMMARY OF THE INVENTION My new machine comprises, in succession:

. A first section for feeding a blank into the top ofa vertical passageway;

2. A first broach having tooth means projecting into said passageway for cutting one of grooves C and D;

3. A second broach having tooth means projecting into said passageway for cutting the other ofgrooves C and D;

l 4. A punch located in a socket at the lower end of the passageway;

5. Means for advancing the blank along said passageway past said first and second broaches and then causing the formation of projection E and depression F in the lower end of the blank by driving it against said punch;

6. A third broach positioned to one side of said passageway;

7. Means for translating the socket, with the blank therein, transversely of the passageway so that the uppermost end of the blank passes beneath said third broach, which forms the chisel point G thereon; and

8. Ejector means actuated upon further lateral movement of said socket.

While broaches, dies or punches, and ejector means, are in themselves well known, my new machine comprising these various elements has the following novel features:

1. Two successive broaching operations, and the punching operation are carried out in the course ofa single stroke;

2. A single second stroke, at right angles to the first, results in both the third broaching and ejection of the completed tumbler.

Thus five distinct operations are carried out in two operating strokes, the second of which may be carried out while the driver for the first is being retracted.

3. The broaches are all readily accessible for adjustment and removal, and the machine can be easily adjusted to accommodate tumblers of different lengths and alter the position of certain surfaces on the tumbler relative to others. This is important because the differences between locks which make them responsive to one key and not another include differences between tumblers.

4. A novel mechanism is provided for cleaning the second broach to remove therefrom the shavings cut from the workpiece.

5. The workpiece is ejected from a position atop the punch by an ejector pin which receives the punch and is slidable thereon. This arrangement helps make it possible to provide a machine having the first feature.

Other objects and advantages of my invention will become apparent from a reading of the following description of a preferred embodiment of the invention, with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view, showing my new locktumbler manufacturing machine as a whole;

FIG. 2 is a detail view, also in perspective, showing the actuating piston with part of the piston broken away to show the push rod carried thereby;

FIG. 3 is a perspective view showing the uppermost broach block, carrying the first broach;

FIG. 4 is a perspective view showing the second broach, with support members and clean-out rods;

FIG. 5 is a detail view showing the tumbler collet and collet support, with the operation during ejection illustrated in phantom lines at the lower right;

FIG. 6 is a detail view, in perspective, looking up at the lowermost broach which forms the chisel point on one end of the tumbler;

FIG. 7 is a perspective view, looking downwardly, showing the portion of the apparatus used to hole the tumbler while moving it laterally as the chisel point is being formed and the tumbler ejected;

FIG. 8 shows the tumbler blank as it machine;

FIG. 9 shows the tumbler after the shallow groove D has been cut by the uppermost broach;

FIG. 10 shows the tumbler after the deeper groove C has been cut by the second broach;

FIG. 11 shows the tumbler after the projection E and depression F have been formed in one end by the punching die; and

FIG. 12 shows the completed tumbler, having a chisel point on one end formed by the final broach.

Like reference characters denote like several views.

parts throughout the DESCRIPTION OF THE PREFERRED EMBODIMENT In describing the preferred embodiment of this machine, a general description referring first to FIG. 1 will be followed by a detailed description of its specific components, and of the operation and performance ofthese components.

Referring first to FIG. I, this shows a lock tumbler fabricating machine wherein an air cylinder support 28 is mounted on an upper plate 20. A pair of side supports 21 and 23 are attached to top plate 20, bottom plate 25, and an intermediate broach support plate 41 to form the main stationary portions of the machine.

Broach plate 41 contains a bushing 29 having a hole 31 in alignment with the center of air cylinder support 28. A singlepointed broach 71 (not seen in FIG. 1, but shown in FIG. 3) is positioned in a slot 33 so that its point protrudes a predetermined distance into the hole.

A second broach 35 (best seen in FIG. 4) protrudes into a passage extending downwardly from the bottom of bushing 29 to the bottom of broach 35.

A lock tumbler blank, previously cut to length, chamfered at one end and conically pointed at the other end by conven tional machinery such as a screw machine, is fed into hole 31, with its chamfered end down. A push rod 61 (FIG. 2) forces the tumbler blank down the hole 31, thereby causing the single pointed broach to broach a groove along the side of the tumbler blank.

Continued force from the broach 35 to cut a second length.

At the end of the stroke of the push red, the tumbler blank is driven into a collet in the slide 37 where the tumbler blank is held until ejected. This slide reciprocates laterally and is actu ated by an air cylinder 39.

During this lateral motion, a third broach (shown at 183 in FIG. 6) and supported in bracket 41, causes a chisel point to be formed at the pointed upper end of the tumbler blank. Ejection at the end of the lateral stroke of the slide 37 completes fabrication of the tumbler, readying it for assembly in the cylinder lock.

push rod will cause the second groove along the side of the tumbler is introduced into the Referring now to FIG. 2, this figure shows a conventional double-acting air cylinder 51 having a sleeve 53 attached to air cylinder support 28. A shaft 55 is attached at one end to the air piston within the cylinder. Its other end 57 is attached to the push rod 61 by means of the nut 59 which cooperates with threads on the end 57. The push rod 61 is provided with longitudinal grooves 62 which provide clearance for the single point broach and the broach 35 (FIG. 1). The head 63 on the push rod 61 is held captive by nut 59 in a manner which permits rotational movement of the push rod 61 relative to piston shaft 55, thereby preventing torsional strain on the piston rod during operation.

Turning now to FIG. 3, this figure is a cutaway view of the broach block 27, showing single-point broach 71 positioned in a slot 33 and retained in position by a key 73 in such a manner that the cutting tooth 75 projects into hole 31 of bushing 29 to a predetermined depth.

The tumbler blanks are received by the tumbler fabricating machine through a tube 81 which is attached to receiving block 83, which in turn is rigidly attached to support 85 on broach block 27.

A feed member 87 having a hole (not shown) in alignment with hole 89 in the receiver block 83 is rigidly attached to the piston rod of air cylinder 91, which, when actuated, pushes the feed member 87 so that the hole therein is brought into alignment with hole 31 in bushing 29. The holes in the receiver block 83 and in feed block 87 are slightly larger in diameter than the tumbler blanks which are received therein, so as to permit free longitudinal movement of the tumbler blanks.

A tumbler blank will therefore arrive in the tube 81, and fall through hole 89 into the hole aligned therewith in feed member 87. Actuation of the air cylinder 91 will cause feed member 87 containing the tumbler blank to slide forward into position over bushing 29. The tumbler blank then falls from the hole in the feed member 87 into the hole 31 in bushing 29. The single point broach tooth 75 will prevent further downward travel of the tumbler blank at this time. Feed member 87 is now retracted to the receiving position shown in FIG. 3 preparatory to receiving the next tumbler.

Push rod 61 (FIG. 2), actuated by air cylinder 51, now enters the hole in bushing 29 and drives the tumbler blank past the tooth 75 of the single-point broach, causing the tooth to broach a longitudinal groove in the tumbler blank.

The feed member 87 has a height which coincides with the length of the tumbler blank being fed into the machine. For this reason a short tumbler blank will require a short feed member 87, and similarly a long tumbler blank will require a tall feed member 87. Since receiving block 83 is rigidly positioned with relation to broach block 27, different heights of bushing 29 are used so that the combined height of bushing 29 and feed member 87 is kept constant.

Feed member 87 is shaped so that when air cylinder 91 is actuated and the member 87 slides forward, the hole 89 in receiving block 83 is blocked at the bottom, thereby preventing advance of the next tumbler blank. Since the feed member height is the same as the length of the tumbler blank being fed therein, only one tumbler blank is introduced into the machine per operation of air cylinder 91.

A slide 84 prevents the tumbler blank from dropping out of the hole in the member 87 until the member 87 is brought into position above the hole 31 in the bushing. This slide may be made in one piece with the bushing 29, as shown in detail at the top of FIG. 3, and mounting in one of the slots in the broach plate 27, in much the same manner as the broach 71. Alternatively, the slide and bushing can be separate parts.

In FIG. 8 a tumbler blank is shown as it is fed into the machine from a conventional screw machine operation. The chamfered end A" is shown at the top and the pointed end 8" is shown at the bottom. The tumbler blanks are fed into the machine with the chamfered end down, hence in inverse position from that shown in FIGS. 8-12.

As the tumbler blank is forced past the single-point broach, a groove D." FIG. 9. is broached along its side longitudinally.

Push rod 61 continues to force the tumbler blank through hole 31 in bushing 29, which provides an entrance to the cylindrical passage 101 in FIG. 4, formed by two blocks 103 and 105 attached to each other. A third block 107 is attached to block 103 and supports a second broach 35. Broach 35 is adjustably attached to member 107 by bolts 109 and 111 which pass through slots in the broach 35 so that the extent to which the broachteeth project into channel 101 can be precisely adjusted after each sharpening of the broach teeth 113. Each tooth of the broach projects into the channel 101 a little further than the tooth above it so that each tooth cuts the groove C (FIG. 10) in the tumbler a little deeper than the preceding tooth.

Thus push rod 61 (FIG. 2) forces the tumbler blank into engagement with the first tooth of broach 35 (FIG. 4) which produces a groove longitudinally along the tumblers side. Continued movement engages the second tooth, thereby deepening the groove in the tumbler. Further movement down channel 101 causes engagement of the tumbler blank with each of the teeth 113 consecutively, each deepening the groove in the tumbler more, resulting in a groove of predetermined depth at the completion of the passage of the tumbler past the broach 35. This completes the third phase in the tumbler fabrication process, resulting in a tumbler blank shown in FIG. 10, having a shallow groove D" and a deep groove C."

The material broached from the grooves in the tumbler is accumulated in circular openings 115 as the tumbler passes the broach. At the completion of the pass, the push rod is retracted from channel 101 preparatory to the next pass. On its return, a series of cleaning rods 117 held in alignment with circular openings 115 by a member 119 are driven into the circular openings 115 by the pivoting motion of the actuator 121, which is swung by an air cylinder (not shown). The metal accumulated in circular openings 115 is now ejected by the cleaning rods 117.

The tumbler blank, upon completion of its pass, is forced into a collet 131 positioned at the bottom of channel 101 in a collect retainer.

FIG. 5 shows the collet 131 supported in collet support 133 and retained therein by plate 135. The collet is provided with a flat peripheral surface 137 for cooperation with a similar flat surface 139 in the retaining plate to prevent rotation of the collet within collet support 133. The bore 141 in the collet is smaller than the diameter of the tumbler blank so that expansion of the collet 131, permitted through means known to those skilled in the art, causes the tumbler blank to be held in position after the retraction of push rod 61 (FIG. 2).

The depth to which the tumbler blank is forced into the collet by the push rod is determined by ejector pin 143 which passes through a depth collar 145. The depth ofthe downward movement of the ejector pin is limited by the engagement of the shoulder 144 on this pin with the top of the depth collar. Ejector pin 143 is provided with a slot 148 for slidably receiving a punch 147 having a flag 149. The flag 149 rests on the depth collar 145 which limits downward motion of both the ejection pin 143 and punch body 147. A small projection 151 at the upper end of the punch body 147 projects beyond the upper surface of ejection pin 143 so that the chamfered end of the tumbler blank is indented as it is driven against the projection 151 by the push rod 61. A slot (not shown) along the axis of the bore in the collet 131 provides slidable engagement with the punch body and permits material being displaced by the indentation in the tumbler to flow thereinto. The punch body is thus partially engaged by the longitudinal slot 148 in ejection pin 143 and partially engaged by the longitudinal slot (not shown) in the bore 141 in collet 131, thereby preventing rotation of the punch body 147 and the ejection pin 143.

The tumbler fabrication now has progressed to the stage shown in FIG. 11, wherein the chamfered end contains indentation F and displaced material in the form ofa projection E." The slots C" and D are axially displaced along the longitudinal side of the tumbler. Pointed end 13" is normally at the top during the fabrication of the tumbler.

Ejection of the tumbler is produced when the entire assembly including collet 131 and collet support 133 is moved laterally by the cylinder 39 and an oblique face 153 at the bottom end of ejection pin 143 engages with the sloping face 155 of anvil 157. This operation is shown in phantom lines at the right of FIG. 5, in which ejection pin 143 has moved upwardly, due to the camming action between the oblique face 153 of ejection pin 143 and the sloping face 155 of anvil 157, to a point at which its upper surface 159 is flush with the upper surface of collet 131. The tumbler, which before ejection was impaled on the projection 151 of punch body 147, is now forcibly removed therefrom since upward movement of the punch body 147 is limited by the engagement of the flag 149 with the bottom of collet 131.

An adjustment made before the machine is started up determines the level at which the ejection pin 143 and punch body 147 are positioned with respect to the various length of the tumblers being processed. Thus, the pointed end of all tumbler blanks must be positioned at a predetermined height above the upper surface of the collet 131. This adjustment is carried out by positioning depth collar 145 on a selected step of a multistep height gauge 161 which in the drawing is provided with five levels of height 163167, each of which positions the depth collar 145, punch body 147, and ejection pin 143 at a height which coincides with the length of the tumbler being fabricated. In the drawing, collar 145 is shown positioned at the greatest height, thus permitting fabrication of the shortest tumbler. Similarly, if height gauge 161 were moved laterally so that depth collar 145 engaged the lowest surface 165, fabrication ofthe longest tumbler would be indicated.

Under these conditions, ejection of the tumbler will begin slightly earlier since oblique face 153 will engage the sloping side 155 of anvil 157 sooner. Both the ejection pin 143 and punch body 147 will move upwardly in unison until flag 149 engages the bottom of collet 131, at which time the tumbler is pried loose from the projection pin 151 as the ejection pin 143 continues its upward motion. The tumbler is then ejected at the end ofthe path of travel of ejection pin 143.

It will of course be appreciated that, instead of using a permanent depth collar supported on a variable height gauge, a supply of depth collars which vary in height may be main tained, and the appropriate collar bearing directly on the slide may be substituted whenever the machine is adjusted to accommodate tumblers ofa different length.

The last operation ofthe fabrication cycle is performed during the lateral movement of the tumbler, before ejection thereof. The pointed end of the tumbler 182 is seen in FIG. 6 to be held by collet 131 (shown in phantom lines). This end is forced into engagement with a broach 181 on the bottom of bracket 41, as the assembly including the collet and collet support is laterally traversed. The broach 181 necessarily comprises two cooperating halves 183 and 184.

The broach halves are held together in a supporting bracket 41 which so supports them that relative motion between the support 41 and the broach halves is impossible. A flange 185 and 187 on each broach half 184 and 183 respectively determines the extent to which the broach halves may protrude through support 41, which has a backing plate 189 holding the broach halves stationary.

The teeth 191 on each of the broach halves are shaped to form a V-shape so that a tumbler forced into engagement therewith will be shaped to have a chisel point. The tumbler blank 182 moves from the left of FIG. 6 to the right. The teeth of broach 181 are such that the teeth first engaging the tumbler remove a small portion thereof. Successive teeth each remove additional material from each side of the pointed end of the tumbler until this end has been shaped as shown at in FIG. 12, which illustrates the tumbler in its completed form.

Turning now to FIG. 7, it will be seen that a slide 37 carries collet I31 and collet support 133 and is laterally slidable on track members 2111 and 203. The slide is driven by air cylinder 39 having a piston rod 205 attached to the slide. A screw 206 in tube 207 provides adjustment for backstop of slide 37, as-

suring proper alignment of the bore 141 in collet 131 with the cylindrical passage 101 shown in FIG. 4. The broach (not visible in FIG. 7) is held in position beneath the support 41 by plate 189. The slide 37 and tracks 2111' and 203 are attached to a pivot plate 209 which is pivotally mounted on the base plate 25 of the machine so that the pivot point coincides with the centerline of hole 31 in bushing 29 of the broach plate 27 (FIG. 1), with the centerline of passage 101 in FIG. 4, and with the center of the collet 141 when it is positioned in its farthest left position as shown in FIG. 7. Three pivot positions are available left" (shown), center, and right, each indexed by the bottom insertion of a position pin through openings 211 in the base plate 25 which may be aligned with a similar hole in pivot plate 209. The anvil 157 (FIG. 5) is rigidly attached to the pivot plate 209 (FIG. 7). Thus as air cylinder 39 (FIG. 7) is actuated, the slide 37 is moved laterally, first causing the tumbler to be shaped by the broach projecting downwardly from support 41, and then, upon en gagement of the ejection pin 143, with the anvil 157 (FIG. 5) at the end of the stroke of air cylinder 39, causing the tumbler to be ejected.

The three positions of the pivot plate make it possible for the machine to manufacture tumblers in which the longitudinal edge of the chisel point is positioned at various angles relative to the diameters bisecting the longitudinal grooves, and it is important that this possibility exist in order to permit the manufacture of as many specifically different tumblers as possible.

It will also be appreciated that the single-pointed broach may be positioned in any of the slots 33 to vary the relative angular position of grooves C and D. It will also be recalled that the members 161 and 29 permit the accommodation of tumblers having different lengths.

It is accordingly possible to produce with this machine a large number of specifically different tumblers by using the many possible combinations of broach position, tumbler length, and pivot plate position which are available.

It will be further appreciated that the various cylinders operate in the following sequence:

1. Cylinder 91 acts to feed in a tumbler blank, and then retracts.

2. Cylinder 51 then acts to drive the blank down. and

retracts.

3. As cylinder 51 retracts, cylinder 39 drives the slide. the collet, and the tumbler blank then held by the collet transversely toward the anvil 157. At the same time the cylinder actuating the pins 73 to clean broach 35 is also actuated.

4. Finally cylinder 51 retracts. The 73 may be retracted and cylinder ously to start a new cycle.

Means may easily be provided for automatically actuating the cylinders in this sequence. Such means may comprise limit switches actuated at the completion of each cylinder stroke and connected to close a circuit which actuates a valve to in itiate the next stroke in the sequence. Alternatively, all cylinders could be controlled from a simple timer.

lclaim:

1. A machine for shaping an elongated cylinder blank including a passageway dimensioned to slidably receive said blank, means for feeding a blank to one end of said passageway, a socket containing a punch in alignment with the other end of said passageway, at least one cutting tooth project into said passageway, means for driving said blank through said passageway past said tooth into contact with said punch, means for moving said socket in a lateral path out of alignment with said passageway, and broach means positioned to act on a blank in said socket as it travels along said lateral path.

2. The machine claimed in claim 1 in which an ejector pin is mounted in said socket for sliding movement between a first position in which it permits a blank in said socket to contact said punch and a second position in which it excludes said cylinder actuating pins 91 actuated simultaneblank from said socket, said machine further comprising an anvil positioned to contact said ejector pin and drive it from said first position to said second position as said socket reaches the end ofsaid lateral path.

3. The machine claimed in claim 2 in which said socket moving means comprises a slide carrying said socket, a track along which said slide is movable, and means on which said track is mounted for pivotal movement about the longitudinal axis of said passageway, said anvil being mounted to move with said track.

4. A machine as claimed in claim 2 in which said ejector pin is provided with a longitudinal slot and said punch is slidable received in said slot.

5. A machine as claimed in claim 1 wherein said broach carries a plurality of cutting teeth which project into said passageway, said teeth having edges which lead into generally circular cavities along one side of said jobs passageway, and a cleaning pin mounted for reciprocal movement in and out of each said cavity,

6. A machine as claimed in claim 5 including means for simultaneously reciprocating said cleaning pins.

7. A machine as claimed in claim 1 wherein the last said means includes two broaches, each having teeth projecting into said passageway at different radial spaced about the axis of said passageway, said broaches being spaced apart from each other axially of the passageway.

8. A machine according to claim 7 with the further provision of mounting means for retaining at least one of said broaches in any one ofa plurality of positions which are angularly spaced about the axis of said passageway so that its angular position relative to the other said broach may be adjusted.

9. The method for producing a cylinder lock tumbler comprising the steps of feeding an elongated cylindrical blank along a predetermined path, subjecting said blank to a first broaching operation along said path wherein a cutting tooth projecting into the path cuts a deep groove longitudinally in the lateral surface of the said blank, subjecting the said blank to a second broaching operation along said path wherein another cutting tooth projecting into the path cuts a shallow groove in the lateral surface of the blank parallel to the said deep groove and spaced therefrom, offset punching the leading end of said blank to provide a lateral projection thereon, transferring said blank laterally from said predetermined path. and moving said blank whereby its trailing end is subjected to a third broaching operation to provide a chisel point thereon.

positions angularly 

1. A machine for shaping an elongated cylinder blank including a passageway dimensioned to slidably receive said blank, means for feeding a blank to one end of said passageway, a socket containing a punch in alignment with the other end of said passageway, at least one cutting tooth project into said passageway, means for driving said blank through said passageway past said tooth into contact with said punch, means for moving said socket in a lateral path out of alignment with said passageway, and broach means positioned to act on a blank in said socket as it travels along said lateral path.
 2. The machine claimed in claim 1 in which an ejector pin is mounted in said socket for sliding movement between a first position in which it permits a blank in said socket to contact said punch and a second position in which it excludes said blank from said socket, said machine further comprising an anvil positioned to contact said ejector pin and drive it from said first position to said second position as said socket reaches the end of said lateral path.
 3. The machine claimed in claim 2 in which said socket moving means comprises a slide carrying said socket, a track along which said slide is movable, and means on which said track is mounted for pivotal movement about the longitudinal axis of said passageway, said anvil being mounted to move with said track.
 4. A machine as claimed in claim 2 in which said ejector pin is provided with a longitudinal slot and said punch is slidable received in said slot.
 5. A machine as claimed in claim 1 wherein said broach carries a plurality of cutting teeth which project into said passageway, said teeth having edges which lead into generally circular cavities along one side of said jobs passageway, and a cleaning pin mounted for reciprocal movement in and out of each said cavity.
 6. A machine as claimed in claim 5 including means for simultaneously reciprocating said cleaning pins.
 7. A machine as claimed in claim 1 wherein the last said means includes two broaches, each having teeth projecting into said passageway at different radial positions angularly spaced about the axis of said passageway, said broaches being spaced apart from each other axially of the passageway.
 8. A machine according to claim 7 with the further provision of mounting means for retaining at least one of said broaches in any one of a plurality of positions which are angularly spaced about the axis of said passageway so that its angular position relative to the other said broach may be adjusted.
 9. The method for producing a cylinder lock tumbler comprising the steps of feeding an elongated cylindrical blank along a predetermined path, subjecting said blank to a first broaching operation along said path wherein a cutting tooth projecting into the path cuts a deep groove longitudinally in the lateral surface of the said blank, subjecting the said blank to a second broaching operation along said path wherein another cutting tooth projecting into the path cuts a shallow groove in the lateral surface of the blank parallel to the said deep groove and spaced therefrom, offset punching the leading end of said blank to provide a lateral projection thereon, transferring said blank laterally from said predetermined path, and moving said blank whereby its trailing end is subjected to a third broaching operation to provide a chisel point thereon. 